As a variable valve mechanism that controls the lift amount, the working angle, and the open/close timing of a valve depending on the operating state of an internal combustion engine, there is conventionally known a variable valve mechanism 100 described in Patent Document 1, as shown in FIG. 7.
This variable valve mechanism 100 is provided with a camshaft 101 that is rotated by a crankshaft (not shown) of the internal combustion engine, and a valve member 103 that opens and closes a valve 102. The camshaft 101 is fixed thereon with a drive cam 104 in an integrally rotatable manner, and supports, in a relatively rotatable manner, an oscillating cam 106 that is provided with a cam surface 105 engaging with the valve member 103.
A control shaft 107 arranged in parallel with the camshaft 101 supports thereon a variable link 109 via an eccentric cam 108, in an oscillatable manner. One end of the variable link 109 is connected to the drive cam 104 with a ring-shaped link 110, whereas the other end of the variable link 109 is connected to the oscillating cam 106 with a rod-shaped link 111. Thus, the power of the drive cam 104 is transmitted to the oscillating cam 106 via the three links 109, 110, and 111, and the oscillating angle of the variable link 109 is changed by the eccentric cam 108. Thereby, the lift amount and the working angle of the valve 102 are changed depending on the operating state of the internal combustion engine.    Patent Document 1: Japanese Patent Application Publication No. JP-A-11-324625